Transcript Chapter 2

Using Information Technology
Chapter 2
The Internet & the World Wide Web
The World of The Internet
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The Internet & the World Wide Web
Exploring Cyberspace
2.1 Choosing Your Internet Access Device & Physical
Connection: The Quest for Broadband
2.2 Choosing Your Internet Service Provider (ISP)
2.3 Sending & Receiving E-Mail
2.4 The World Wide Web
2.5 The Online Gold Mine: More Internet Resources,
Your Personal Cyberspace, E-Commerce, & the Economy
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2.1 Choosing Your Internet Access
Device & Physical Connection

This section discusses the different
technologies used to connect individuals to
the internet including:
 1. Access device: a personal computer
with a modem
 2. Physical connection: a telephone
line
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Modem
 Is a device that converts a digital signal to an analog
signal and vice versa. Modem is short for
modulate/demodulate
 Conversion from digital to analog signals is called
modulation and reverse process is called
demodulation.
 Modem has various types.
 External modem
 Internal modem
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Physical connection

The wired or wireless means of
connecting to the Internet.
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Data Transmission Rates

Data is transmitted in bits per second.
 bps stands for bits per second. A bit is the smallest unit
of information used by computers. A computer with an
older modem might have a speed of 28,800 bps per
second.
 Kbps stands for kilobits per second. This is the most
frequently used measure.
 Mbps stands for megabits per second
 We at NIIT have 1 Mbps leased line for internet
 Gbps stands for gigabits per second
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Bandwidth
- an expression of how
much data can be sent
through a communications
channel in a given amount
of time
Broadband - very high
speed connection
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Download & Upload
Download - to transmit
data from a remote
computer to a local
computer
Upload - to transmit data
from a local computer to a
remote computer
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Telephone (Dial-Up) Modem: Low Speed but
Inexpensive & Widely Available
Modem - device
that sends and
receives data over
telephone lines to
and from computers
Most modems
today have a
maximum speed of
56 Kbps.
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High-Speed Phone Lines: (No dialup line)
Packet Switching
Integrated Services Digital network (ISDN) - hardware and
software that allows voice, video, and data to be communicated
over traditional copper-wire telephone lines. Speeds up to 128
kbps.
Digital Subscriber Line (DSL) - also uses regular phone lines
but much faster than ISDN. Download speeds 1.5 – 8.4 Mbps
 One for telephone wire is splitted for voice and one for
data. 64kbps is required for human voice data transfer
 ADSL
T1 - A traditional trunk line that carries 24 normal telephone
circuits and has a transmission rate of 1.5 Mbps. Good for
business.
 23 lines are for usage and 1 is for connectivity control
 23 different phone numbers
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ISDN
 Type of line that could be used directly for digital
transmission. End to End Digital transmissions.
 ISDN adapter can move data at 128,000bps , a vast
speed improvement over any modem
 ISDN circuit includes two phone lines, so a user can
use one line to connect to the internet and other to
talk on the phone at same time.
 Expensive
 High speed and high capacity
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High-Speed Lines
Cable :

Close Competitor to DSL
Speeds up to 10 Mbps
Fiber Optics: Can support speeds up to 2 Gbps
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Assignment 2 -- Due Oct 23rd Tuesday.
 Study: Compare and Contrast ISDN, DSL, and Cable
Internet?
 Submission: What are some of the DSL options
available?
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Wireless Systems: Satellite & Other
Through-the-Air Connections

Satellite: With a pizza-size satellite dish on
your roof, you can receive data at the rate of 400
Kbps from a communications satellite, a space
station that transmits radio waves called
microwaves from earth-based stations.

Other wireless connections: In urban areas,
some businesses are using radio waves
transmitted between towers that handle cellular
phone calls, which can send data at up to 155
Mbps.
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2.2 Choosing Your Internet Service
Provider (ISP)
ISP - a company
that connects you
through your
communications
line to its servers,
or central
computer, which
connect you to the
Internet via another
company’s network
access points
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2.3 Sending & Receiving E-Mail
E-Mail Software & Carriers
Buy e-mail software
Get e-mail program as
part of other computer
software (such as
browser)
Get e-mail software as
part of your ISP
package
Get free e-mail
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E-Mail Addresses
Domain Name
[email protected]
User name: Jane_Doe
Domain : earthlink
Top-level domain: .net
Two-letter country extension: .uk
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Attachments

Attachments: Files attached to an e-mail
message in their own format. Individuals can attach
pictures, sounds, videos, and other files to e-mail
message.

Note: Many viruses ride along with e-mail as
attached files. Never open an attached file from an
unknown source
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Instant Messaging
Instant messaging (IM) - allows any user on a given
e-mail system to send a message and have it pop
up instantly on the screen of anyone else logged
onto that system
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Chat Applet

A rectangular area containing a document or
activity so that users can exchange messages almost
instantaneously while operating other programs.
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 Mailing Lists: E-Mail-Based Discussion Groups
 List-serves - e-mail mailing lists of people who
regularly participate in discussion groups
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Netiquette: Appropriate Online Behavior
(a) Don’t waste people’s time.
(b) Don’t say anything to a person online that you
wouldn’t say to his or her face.
•(c) Consult FAQs: Most online groups post FAQs--for
Frequently Asked Questions--that explain expected
norms of online behavior for a particular group.
(d) Avoid Flaming: Writing an online message that
uses derogatory, obscene, or inappropriate language.
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Netiquette: Appropriate Online Behavior
(e) Emoticons: Keyboard-produced pictorial
representations of expressions.
(f) Avoid SHOUTING: Use of all-capital letters is
considered the equivalent of SHOUTING.
(g) Avoid Sloppiness: Avoid spelling and grammatical
errors. Try to avoid criticizing others’ sloppiness.
(h) Do not send large file attachments, unless
requested. This may tie up your country cousin, who has
a slow dial-up connection, when he or she badly needs to
use it.
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Netiquette: Appropriate Online Behavior
(i) When replying, quote only the relevant portion.
If you’re replying to just a couple of matters in a
long e-mail posting, don’t send back the entire
message. This forces your recipient to wade
through lots of text to find the reference. Instead,
edit his or her original text down to the relevant
paragraph and then put in your response
immediately following.
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Spam: Unwanted Junk E-Mail
Delete without opening the message
Never reply to a spam message!
Enlist the help of your ISP or use spam filters
Fight back
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2.4 The World Wide Web



The Multimedia makes the Web
attractive and inviting.
The Hypertext makes the web navigable.
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Hypertext

A system in which documents scattered across
many Internet sites are directly linked, so that a word,
phrase or an image in one document becomes a
connection to a document in a different place.

The term hypertext was coined by American
computer scientist Ted Nelson in 1965 to describe
textual information that could be accessed in a
nonlinear way. He used the prefix hyper to describe
the speed and facility with which users could jump to
and from related areas of text.
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Hypertext Markup Language (HTML)

The set of special instructions (called
"tags" or "markups") that are used to specify
document structure, formatting, and links to
other documents.

HTML is a subset of a broader language called
Standard Generalized Markup Language (SGML),
which is a system for encoding and formatting
documents, whether for output to a computer screen
or to paper.
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HTML Script
 <html>
 <head>
 <script language="javascript"
src="http://us.i1.yimg.com/us.yimg.com/i/mc/mc.js">
 </script>
 <meta http-equiv="pics-label" content='(pics-1.1
"http://www.icra.org/ratingsv02.html" l gen true for
"http://mail.yahoo.com" r ( nz 0 vz 0 lz 0 oz 0 ca 1))'>
 <title>Yahoo! Mail - The best free web-based email!</title>
 </head>
 <body bgcolor=#ffffff
 onload="document.login_form.login.focus();">
 <center>
 <script language="JavaScript">
 <!- hasMsgr = 0;
 /*
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The Web & How It Works

Web-- A domain on the computer

Site - a computer with a domain name

Website - the location of a web domain
name in a computer somewhere on the
Internet
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Web page

A Web page is a document on the
World Wide Web on a Website that can
include text, pictures, sound, and video.
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Designing Web Pages


Professional Web page designers can
produce a page for customers, or the
customers can do it on their own using a menudriven program included with a Web browser or
a Web-page design software package such as
Microsoft FrontPage or Adobe PageMill.
LAB WILL FOLLOW! 
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Browsers – Software for connecting with
websites

In computer science, a program that enables a
computer to locate, download, and display documents
containing text, sound, video, graphics, animation, and
photographs located on computer networks.
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URLs – Addresses for Web Pages

Uniform Resource Locator (URL) is a method of
naming documents or places on the Websites.

A URL is a string of characters that identifies the
type of document, the computer the document is on, the
directories and subdirectories the document is in, and
the name of the document.
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A URL
 http://www.nps.gov/abli/index.htm
 Protocol : http
 Domain name: www.nps.gov
 Directory name: abli
 File name: index.htm
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Using Your Browser to Get Around the Web
Home page - the first page you see when you start up
your browser
Getting around:

Back - takes you back to the previous page

Forward - takes you to a page you returned from

Home - takes you to your home page
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Using Your Browser to Get Around the Web
History list - list accessible from browser’s toolbar that
allows you to return to a page you have recently visited
Bookmarks or favorites - your favorite URLs stored in a
list to permit frequent visits without retyping the URLs
Simultaneous viewing of two pages via File menu’s
“New” item
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Using Your Browser to Get Around the Web
Interactivity--hyperlinks,
radio buttons, and fill-in
text boxes
Radio buttons - little
circles located in front of
various options; selecting
an option with the mouse
places a dot in the
corresponding circle
Radio buttons and textbox
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Web Portals: Starting Points for Finding
Information
Web portal - website that groups together in one
convenient location popular features such as search
tools, e-mail, electronic commerce, and discussion
groups
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Web Portals: Starting Points for Finding
Information
After logging on,
you can:
Check the home
page for general
info
Use the
directories to find a
topic
Use keyword to
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Search Engine

Computer software that compiles lists of
documents, on the World Wide Web (WWW), and the
contents of those documents. Search engines respond
to a user entry, or query, by searching the lists and
displaying a list of documents that match the search
query. Some search engines include the opening portion
of the text of Web pages in their lists, but others include
only the titles or addresses (URLS) of Web pages.
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Four Types of Search Engines
Human-organized search sites
Computer-created search sites
Hybrid search sites
Metasearch sites
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Human-organized search sites

Unlike indexes created by computers,
humans can judge data for relevance and
categorize them in ways that are useful to you.
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Computer-created search sites

These are assembled by software "spiders"
that crawl all over the Web and send back
reports to be collected and organized with little
human intervention. The downside is that
computer-created indexes deliver you more
information than you want.
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Hybrid search sites

Hybrid sites generally use humans
supplemented by computer indexes. The
idea is to see that nothing falls through the
cracks.
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Metasearch sites

Metasearch sites send your query to several
other different search tools and compile the
results so as to present the broadest view.
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Tips for Smart Searching
o Start with general search tools.
o Choose search terms well and watch spelling.
o Use phrases with quotation marks rather than
separate words
o Put unique words first in a phrase
o Use Boolean operators--AND, OR, NOT, and + and –
signs--to make searching more precise
o Read the Help or Search Tips section
o Try an alternate general search site or a specific
search site
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Multimedia on the Web
 Plug-ins
 Applets
 Text and Images
 Animation
 Video
 Audio
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Plug-ins

A program that adds a specific feature to a
browser, allowing it to play or view certain files.
Plug-ins are required by many Web sites if users
want to fully experience the content. E.g in order
to view a PDF file, the Adobe Reader plug in is
required
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Some Common Plug-ins
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Applets

Small application programs that can be quickly
downloaded and run by most browsers.
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Text and Images
 Most Web pages combine both text and
images.
Animation
Animation is the rapid sequencing of still
images to create the appearance of motion.
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Video


Video can be transmitted in two ways.
• A file, such as a movie or video clip, may
have to be completely downloaded before
you can view it.

• A file may be displayed as streaming video,
the process of transferring data in a
continuous flow so that you can begin
viewing a file even before the end is sent.
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Audio

Audio, such as sound or music files, may also
be transmitted in two ways:

• Downloaded completely before they can be
played.
• Downloaded as streaming audio, which allows
users to listen to the file while the data is still
being downloaded to the computer. A popular
standard for transmitting audio is RealAudio,
which compresses sound so that it can be
played in real time.
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Push Technology & Webcasting
Push technology - software that automatically
downloads information to your computer
Webcasting - customized text, video, and audio sent to
you automatically on a regular basis
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The Internet Telephone & Videophone
Internet telephony - using the Net to make phone calls,
either one-to-one or for audioconferencing
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2.5 The Online Gold Mine: More Internet
Resources, Your Personal Cyberspace, ECommerce, & the E-conomy
o File Transfer Protocol (FTP)
o Telnet
o Newsgroups
o Real-Time Chat
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File Transfer Protocol (FTP)

FTP is a method whereby users can connect to a remote
computer called an FTP site and transfer publicly available
files to a microcomputer’s hard disk. The free files cover
nearly anything that can be stored on a computer: software,
games, photos, maps, art, music, books, and statistics.

In computer communications, on the Internet and other
networks, a method of transferring files from one computer to
another. The protocol is a set of rules that ensures a file is
transmitted properly to the receiving computer. A computer
that stores files that can be retrieved using FTP is called an
FTP site or FTP server. FTP is part of the Transmission
Control Protocol/Internet Protocol (TCP/IP), the system that
enables different types of computers and networks on the
Internet to communicate.
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Telnet

A program or command that allows users to connect
to remote computers on the Internet using a user name
and password.

Telnet, protocol, or set of procedures, that enables
a user of one computer on the Internet to log on to any
other computer on the Internet, provided the user has a
password for the distant computer or the distant
computer provides publicly available files or data. Telnet
is also the name of a computer program that uses those
rules to make connections between computers on the
Internet. Many computers that provide large electronic
databases, like library catalogs, often allow users to
telnet in to search the databases. Many resources that
were once available only through telnet have now
become available on the easier-to-use World Wide Web.
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Newsgroups

A giant electronic bulletin board on which
users conduct written discussions about a specific
subject.
Real-time chat

Participants have a typed discussion ("chat")
while online at the same time, just like a
telephone conversation except that messages are
typed rather than spoken.
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Your Personal Cyberspace
Relationships--online matchmaking
Education--the rise of distance learning
Health--patient self-education
Entertainment--amusing yourself
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E-Commerce
E-tailing--retail commerce online
Auctions--linking individual buyers and sellers
Online finance--trading, banking, and e-money
Online job hunting
B2B commerce
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